Four families of very young asteroids, all under 7 million years old, have been pinpointed in the principal Asteroid Belt located between Mars and Jupiter, according to a study carried out by Sao Paulo State University (UNESP) in Guaratingueta, Brazil, and published yesterday in the Monthly Notices of the Royal Astronomical Society journal.
“We identified the new families by means of numerical simulation using the backward integration method (BIM), which is much more precise than other methods for dating asteroid families. But BIM only works for really young families that are less than 20 million years old,” said Valerio Carruba, the study’s leading author.
“When an asteroid family is formed, all ascents and ascending nodes are aligned, but as the family evolves, the alignment is lost due to gravitational disturbances produced by the planets and possibly some massive asteroids,” Carruba, who is a professor in UNESP’s Mathematics Department, added.
Such extremely young asteroid families can only form either by collision or by fission
When a couple of asteroids collides, either one or both of the two space rocks may break up, creating a family with multiple objects. On the other hand, fission means the expulsion of the matter by a precursor body, because it gained a very rapid rotation around its axis and had a collision or it recently expulsed a subsidiary body that ruptured.
“One of the four families we identified was undoubtedly formed by a collision event. It’s very likely that the collision was the origin of another. The rest were recently identified, and we need more studies to formulate a hypothesis regarding their formation,” explained Carruba.
The asteroids in the Main Asteroid Belt are not uniformly dispersed, as Carruba claims. A number of different areas have developed within the belt because of the highly intricate gravitational interaction of so many different space objects there and mainly due to the powerful gravitational field of Jupiter.
The age estimations of asteroid families in the Asteroid Belt vary from a few million to several hundred million years old. The oldest family found there is aged approximately 4 billion years, so it was part of the earliest phase of the Solar System’s formation. Accordingly, the four extremely young asteroid families Brazilian scientists found are among the youngest space rocks in the Asteroid belt.